A roller-coaster ride for AGVs

After ups and downs in user acceptance, automatic guided vehicle systems regain favor, due to greater reliability and improved navigation methods.

By Tom Feare, Senior Editor -- Modern Materials Handling, 1/1/2001

Two years from now, in 2003, automatic guided vehicles (AGVs) will mark 50 years of applications in the U.S. for materials handling. Yet, even with a half century history of uses–and many of them highly successful–there seems to be a degree of skepticism, an attitude of "I'm from Missouri, show me about applying this technology in America."

There are some reasons for this view based on past reliability problems and some longer-than-expected payback periods.

"A lot of AGV systems in the 1980s," says HK Systems' AGV product manager Randy Winger, "were oversold and underdelivered." Suppliers tried to meet goals they couldn't achieve. As a result, "marginal companies dropped out of the business."

But things have changed and there are now a number of strong benefits from the technology. The systems can cut labor costs, reduce product damage, and help avoid accidents, for example.

AGVs "can do the dull, dangerous, and repetitive tasks," as Michael Urban, vice president, Mentor AGVS, says. But these systems go even further.

Noting that many AGV installations in the U.S. recently have been in manufacturing, Swisslog vice president Brad Moore underscores how "AGVs provide flexibility in continuous processes." They offer less rigidity in moving materials, and do so without the inflexibility often associated with fixed-path, mechanized, or automated transportation methods, he adds. "They're also necessary to the process."

And that's the case in both manufacturing and distribution. One successful use of AGVs is described in this issue's Warehouse of the Month about JCPenney. And last month's Manufacturing Spotlight feature about Delphi Automotive Systems demonstrates how AGVs perform in a production environment

Fluctuating orders

Despite these and other successes, AGVs clearly have been on a roller coaster ride over the years. Orders for AGV systems sold in the U.S. have fluctuated. Over the last decade, orders started with a high of 100 systems in '91, reached a low of 39 systems in '96, and amounted to system counts of 65 in '97, 56 in '98, and 43 in '99. (The year 1999 is the latest for which the Material Handling Industry of America has order data from its Automatic Guided Vehicle Systems product section.)

Most vendors we spoke with for this article were very pleased about their business for the year just finished. Total systems ordered for 2000 "absolutely were up from 43 in 1999," says Swisslog's Moore. The challenge of finding workers in a tight labor market "is pushing automation across the board, not just in AGVs. Labor availability is a concern for a lot of our clients," he adds.

AGV Products' marketing manager Debbie Bishop concurs with Moore's positive outlook. And she notes that companies also are finding users in some innovative applications. So the year 2000 statistics from MHIA, when released later this year, bear watching.

Counts of systems don't tell the whole story, of course. The number of vehicles is another way to gauge acceptance and popularity of AGVS.

A study on AGVs, which was conducted by Kirk Redwine, manager, market development, at the consulting firm Lockwood Greene, arrives at these findings. U.S. users buy about 400 AGVs annually. In contrast, Europeans and Japanese users purchase far more AGVs. They roughly buy 1,800 and 2,300 vehicles a year, respectively, according to Redwine.

Some of these overseas AGVSs may be less costly systems with fewer vehicles than in the U.S. Even so, here's the underlying point, says Redwine: "There's a tremendous, as yet unrealized potential, for AGV systems in the U.S."

But there's a big "if." If U.S. manufacturers of AGVS can, as Redwine says, "break through the barriers of user concerns over past reliability and educate industry on the capabilities of the technology;" then that potential has a chance of being realized.

But the battle for acceptance has other fronts too. To begin, users need to achieve reasonable return on investment (ROI), Redwine adds. And when the cost of an average vehicle in an AGV system today in the U.S. runs about $100,000, ROI is critical to acceptance of the technology.

Unfortunately, the ROIs on some of the older AGV systems made in the 1970s and 1980s weren't what they were projected to be, as Mark Longacre, FMC marketing manager for AGVs, notes. Payback periods were extended to a much longer than acceptable time frame.

These AGVs of the 1970/80s did reduce operating personnel labor costs. But these savings tended to be offset by added labor costs for maintaining the AGVs, Longacre observes."

Newer systems, however, have a far better track record for lower maintenance needs and higher reliability. FMC, Longacre says, has focused on eliminating problem components, for example, and designing its own critical parts where none could be previously found available on the market.

AGV suppliers have invested money into developing componentry and making vehicles more rugged, adds HK's Winger.

Earl Raynal, Jr., sales manager for Control Engineering Corp., a Jervis B. Webb division, notes how advances in AGV electronics have paralleled those in TVs, cell phones, and PCs. "The component count has gone way down. We now have from a third to half the amount of wiring and connectors in our AGVs than we did ten years ago," he says, which makes for greater reliability.

Consequently, he continues, "there are a number of systems now that are absolute gems. They have high uptime. And they are process critical." If the AGVS goes down, everything stops. But that seldom happens, he says.

Even so, an AGVS isn't maintenance free. That's particularly relevant given that many systems run 24 hours daily, 7 days/week, as HK's Winger notes.

Today's AGV suppliers

Rationalization reshaped the U.S. AGV industry heading into the 1990s, as Amerden's Neville Croft, director of sales, and others observe. Now, in early 2001, the list of major suppliers providing AGVs for uses in materials handling numbers around 14 firms. Industry speculation suggests that an imminent acquisition or two may further thin these ranks to a baker's dozen or less. But the remaining firms stand ready to provide a wide range of AGVs for varied uses.

Towing and unit load handling are the more common applications for AGVs. But the list of uses doesn't stop there.

AGV systems began in the U.S. with towing vehicles in a grocery warehouse. To this day, the towing/tugging AGVS is a "sleeper business" that's "still going strong," says Garry Koff, senior AGV product specialist at Rapistan Systems.

The basic principle is simple, he adds: "A horse can pull more than it can carry." Paybacks, moreover, "can be better than those from unit-load AGVS," he maintains, "because the tugger systems can save more in people time."

Unit-load vehicles are the other major category of AGVs, meantime. They are paying their way in different kinds of usage. In typical applications, they can be equipped with a conveyor deck, a lift/lower deck or table, an assembly platform, or with special handling devices. Suppliers also offer a variety of forklift-style vehicles for unit load handling. In some instances these vehicles are very similar in design and operation to manually driven lift trucks.

In some applications, such as the Delphi plant, AGVs handle smaller, tote-sized loads. This installation has AGVs with a customized deck made up of three roller conveyors for totes.

Suppliers generally stand ready to customize their regular product offerings if a standard vehicle won't work in your application. When contemplating an AGVS and before contacting potential suppliers, try doing some homework first. Be ready to describe the materials being moved. Here are some others questions for which you need the answers:

• What are the maximum and minimum load weights?

• What are the length/width/ height dimensions of these biggest and smallest loads?

• Will the load be on a pallet, skid, or sheet, or will it be in specialized racking?

• How do you want to move the load on and off the AGV? Will it be by forklift, conveyor, overhead crane, or some other means? How will you initiate load movement?

• Will you need pickup/delivery stands, and if so, how many? Powered or non-powered?

• What are the expected routes for AGVs and the distances to be traveled throughout your facility?

What kind of guidance system?

Next comes the hard part–for both you and your potential AGV supplier: What type of navigation or guidance system should you choose to control AGV traffic and track vehicle locations in your potential materials handling application? The short answer: It all depends.

Several different kinds of technology guide today's AGVs. These systems instruct vehicles to follow either a fixed path or an open path.

Within the fixed path category are wire-guided systems buried in the floor. There are also above-surface guidance systems where AGVs follow a path of magnetic tape, a photo-sensitive chemical strip, or a photo-reflective tape. Open-path systems are generally laser-guided or inertially guided AGVS in the U.S.

As you consider guidance options, here's advice from Tom Allen, a partner in Allen Zeiler Technical Consulting.

"Don't get hung up on any one guidance technology," Allen urges. He also cautions potential users not to select a guidance method "just because it's the latest and greatest." Wire-in-the-floor may work best for your application.

Laser-guided and inertially-guided AGVS are the navigation methods of choice for many current materials handling systems, most vendors say. But they also offer wire-guidance as well.

Cost differences between these open path systems and wire-guided AGVS are shrinking, meantime. There are tradeoffs, says Swisslog's Moore. Cost per vehicle may be 5% to 10% higher for laser- and inertially-guided systems. But there's a lesser expense for installation for these open path methods versus extra costs for cutting into the floor and burying wire for a fixed-path AGVS.

Both laser-guided and inertially-guided systems now have improved their accuracy so that they now position vehicles to a fraction of an inch away from a point on the floor.

Fixed, above-surface pathway systems tend to be used only for light-duty applications, such as AGVS in hospitals and healthcare operations, says Swisslog's Moore, and not in heavier-duty materials handling.

Systems working off the navigational guidance from earth-orbiting GPS satellites are being tried in some overseas seaports, meanwhile. They work outdoors where the satellites' signals can be picked up. But positional accuracy of 5 to 10 ft is hardly good enough for indoor applications, suppliers stress.

Yet, within 3-5 yr, says Rapistan's Koff, localized GPS-like technology with radio frequency transceivers mounted within a facility may well be added to the choices for materials handling. FMC's Longacre notes his firm already has the technology to do indoor, local GPS guidance. "The accuracy of these systems is comparable with other navigation technologies, but right now the price is prohibitive."

A $5,000 AGV bumper?

"One of the hottest developments in AGV technology," says Mentor's Urban, is the laser bumper. Instead of a mechanical front bumper, the AGV has a virtual, non-contact bumper. It consists of a laser sensor sending out a beam ahead of the AGV and detecting objects in the path of travel. Laser bumpers work well on forklift-type AGVs where otherwise only small mechanical bumpers are feasible.

Swisslog's Moore says there are "viable opportunities" to use the laser bumpers, and "especially for long AGV runs at high speed, if the technology is applied properly." But as he observes, pedestrians in these applications often miss the mechanical bumpers. "People feel safer if there's a physical contact point on the AGV." There's a psychological factor favoring the mechanical bumper, if nothing else.

This virtual, laser bumper technology isn't cheap, nor is it for everyone. Cost per bumper is around $5,000 or more compared to $700 for a standard, mechanical bumper. Choosing between the two, says Rapistan's Koff," may depend upon how often the user breaks a bumper."

Less black magic

AGVs are more user-friendly now, says Koff. "We all had black magic technology years ago, and that was also black magic to our customers." Now, however, AGV systems are much more user-configurable. It's like going from an MS-DOS computer system to Windows 95. "Instead of issuing cryptic commands, we do point-and-click steps now," Koff says. Software advances, moreover, also enable AGV vendors to install and configure systems more rapidly, adds Control Engineering's Raynal.

Driverless walkies, pallet trucks?

The wall between AGVs and conventional, operator-run lift trucks is starting to crumble a bit, meantime.

Forklift-style AGVs are beginning to take over some unit-load handling tasks performed previously by driver-aboard lift trucks. In some instances these vehicles are fully automated, as FMC's Longacre points out. And in other cases they are hybrids. "A hybrid is manually operated for unit load pickup and dropoff," he says, "then it runs fully automated travelling from point A to B."

One factor favoring hybrid operation is vehicle cost. The price tag on a simple, laser-guided hybrid vehicle is approximately half that of a fully automated AGV, the FMC exec says.

Conventional lift truck manufacturers are working with AGV suppliers in some of these applications. Man-up, wire-guided turret trucks have been fully automated for work in what is a virtually "lights-out" warehouse (photo) in the U.S. The turret trucks then transfer loads to fully automated forklift AGVs.

Electric hand trucks–such as pedestrian pallet trucks, walkies, walkie/riders, stackers, and straddle vehicles–are being equipped with varying levels of AGV-like automation in Europe. These cooperative efforts between lift truck maker and AGV supplier are as yet unmatched in the U.S., however.

NDC Automation vice president Mike Thornton explains his firm's approach: A standard walkie pallet truck is equipped with an onboard terminal and laser guidance. So equipped, a $12,000 stacker or straddle truck becomes a $75,000 or more semi-automated forklift-AGV, Thornton says. Add some laser-guided pallet finding technology at extra cost and the vehicle becomes fully automated.

At a quick glance, these automated walkies and pallet stackers look like the first AGV in the U.S., except for their forks. (The 1953 model was an electric tow tractor working a grocery warehouse by running off an overhead trolley wire.) Look under the hood, however, of any of today's AGVs and they readily show that they have far more smarts than their ancestor of a half century ago.

Potential benefits from AGV systems

• Automatically perform dull, repetitive, or dangerous tasks

AGVs help bring beverage cans to consumers

Bring beverage cans to consumers by automatic guided vehicle? Well, hardly. But laser-guided AGVs do handle huge coils of aluminum metal ready to be turned into drink cans at the Oswego, N.Y. plant of Alcan Aluminum Corp. An AGV can pick up and transport a coil weighing up to 40,000 lb, then move it to a packaging line at Alcan.

What's your IQ score on AGVs?

To test what you have learned about AGVs, try answering questions from consultant Tom Allen. Here's part of a pop quiz he gave at a tutorial talk at last year's NA 2000 event. True or false:

1. AGVS are reliable.

2. Wire-guidance systems are not flexible.

3. AGV expenditures are easy to put off.

4. KISS is essential for AGV success.

5. AGVs will replace all forklifts.

6. Alfalfa has been harvested by an AGVS.